Leprosy Overview

Leprosy, also called Hansen's disease, is a chronic infectious disease that
primarily affects the skin, the peripheral nerves, the mucosa of the upper
respiratory tract, and the eyes. Leprosy can lead to progressive permanent
damage of these structures, and the resulting devastating disfigurement and
disability has led to the historical social stigma and isolation (leper
colonies) of those affected by the disease.

Historically speaking, leprosy has existed since at least 4000 BC, and the disease was present and described in the ancient civilizations of China, India, and Egypt. The first known written reference to the disease on Egyptian papyrus dates from about 1550 BC. It is believed that leprosy was brought to Europe by the Romans and the Crusaders and that later the Europeans brought it to the Americas. For centuries, leprosy remained a poorly understood disease characterized by human suffering and social isolation. In 1873, G.A. Hansen discovered the bacterial cause of this infectious disease. The first medication breakthrough occurred in the 1940s with the development of the drug dapsone, and later it was discovered that the bacteria which caused leprosy was more effectively killed by using multiple medications.

Leprosy is a curable disease with the use of multidrug therapy (MDT). In 1991, the World Health Assembly passed a resolution to eliminate leprosy as a public-health problem by the year 2000. The elimination of leprosy was defined as a prevalence rate of less than one case per 10,000 people on a global level. In the year 2000, the global elimination of leprosy, according to the prevalence rate, was achieved. With assistance from the World Health Organization (WHO), MDT has been distributed free to all patients with leprosy since 1995. Though leprosy is still endemic in a few developing countries (primarily in the tropics), there has been a dramatic worldwide decrease in the prevalence of the disease due to this successful public-health initiative. Over the past 20 years, close to 16 million leprosy patients have been cured, and the prevalence rate of the disease has decreased by 90%. Leprosy has been eliminated from 119 countries out of the 122 countries where previously leprosy was deemed a public-health concern in 1985. Official reports from 115 countries around the world reported 232,857 new cases of leprosy in 2012, with about 95% of these cases occurring in only 16 different countries. Countries in which leprosy is more commonly found include Angola, Bangladesh, Brazil, China, Central African Republic, Ethiopia, India, Indonesia, Madagascar, Myanmar, Nepal, Nigeria, Philippines, Sudan, South Sudan, Sri Lanka, United Republic of Tanzania, Democratic Republic of the Congo, and Mozambique. In the United States, according to the National Hansen's Disease Registry, 213 new cases were reported in 2009, with 65% of these cases occurring in California, Florida, Hawaii, Louisiana, New York, Texas, and Massachusetts. On average, 150-250 new cases of leprosy are diagnosed each year in the United States, with most cases occurring in immigrants. However, because the bacteria can be found in wild animals (for example, armadillos, chimpanzees), it is unlikely that leprosy will be totally eliminated like smallpox.